#include <stdio.h>

char*  _strcat(char *str1, char *str2)
{
	int len1 = strlen(str1);
	int len2 = strlen(str2);
	int i;
	char *p = malloc(sizeof(char)*(len1+len2));
	for (i = 0; i <len1;i++) {
		p[i] = str1[i];
	}
	for (i = 0; i < len2; i++)
	{
		p[i + len1] = str2[i];
	}
	p[len1+len2] = '\0';
	return p;
}
int main()
{
    puts(_strcat("aaa","Bbb"));
    return 0;
}